1. Technical Field
Embodiments of the subject matter disclosed herein generally relate to methods and systems and, more particularly, to mechanisms and techniques for displaying/retrieving sensor information of a subsea device.
2. Discussion of the Background
During the past years, with the increase in price of fossil fuels, the interest in developing new production fields has increased dramatically. However, the availability of land-based production fields is limited. Thus, the industry has now extended drilling to offshore locations, which appear to hold a vast amount of fossil fuel.
The existing technologies for extracting the fossil fuel from offshore fields use a System 10 as shown in FIG. 1. More specifically, the System 10 includes a vessel 12 (e.g., oil rig) having a reel 14 that supplies power/communication cords 16 to a controller 18. The controller 18 is disposed undersea, close to or on the seabed 20. In this respect, it is noted that the elements shown in FIG. 1 are not drawn to scale and no dimensions should be inferred from FIG. 1.
FIG. 1 also shows a wellhead 22 of the subsea well and a drill line 24 that enters the subsea well. At the end of the drill line 24 there is a drill (not shown). Various mechanisms, also not shown, are employed to rotate the drill line 24, and implicitly the drill, to extend the subsea well.
However, during normal drilling operation, unexpected events may occur that could damage the well and/or the equipment used for drilling. One such event is the uncontrolled flow of gas, oil or other well fluids from an underground formation into the well. Such event is sometimes referred to as a “kick” or a “blowout” and may occur when formation pressure inside the well exceeds the pressure applied to it by the column of drilling fluid. This event is unforeseeable and if no measures are taken to prevent it, the well and/or the associated equipment may be damaged. Although the above discussion is directed to subsea oil exploration, the same is true for ground oil exploration.
Thus, a blowout preventer (BOP) might be installed on top of the well to seal the well in case that one of the above mentioned events occurs and threatens the integrity of the well. The BOP is conventionally implemented as a valve to control the pressure either in the annular space between the casing and the drill pipe or in the open hole (i.e., hole with no drill pipe) during drilling or completion operations. More recently, a plurality of BOPs has been installed on top of the well for various reasons. FIG. 1 shows two BOPs 26 or 28 that are controlled by the controller 18.
The BOPs are provided in a BOP stack 45 as shown in FIG. 2. Other equipment is also provided on the BOP stack 45, e.g., MUX POD 40 or 42, etc. The MUX POD is configured to communicate with the vessel 12 and also with the BOPs and other equipment present on the BOP stack 45. The information “communicated” may include electrical signals and/or hydraulic pressure. Most of the electrical signal are originally transmitted from the surface, i.e., from the rig or vessel, by the operator of the well. The electrical signals are directed to the MUX POD (see elements 40 and 42 in FIG. 2), a component of the BOP stack that is usually provided on a Lower Marine Riser Package (LMRP) part 44 of the BOP stack 45. For redundancy purposes, two MUX PODs 40 and 42 are provided on the BOP stack 45. The BOP stack 45 also includes a lower BOP part 46 that includes various BOPs 26 and 28. The LRMP part 44 is detachably attached to the lower BOP part 46. The LRMP part 44 is attached to an end of a marine riser 49 that goes to the vessel 12. The lower BOP part 46 is traditionally attached to the wellhead 22 of the well (not shown).
Various sensors and valves are provided on the BOP stack to monitor its status and the surrounding environment. Information associated with the sensors and valves need to be provided to the operator on the vessel for controlling the BOP stack. Thus, as shown in FIG. 3, a traditional arrangement 80 has the information provided to the MUX POD 82 or 84 (and then to the operator) from sensors 86 and 88 through a remote terminal unit RTU 90. Voltage is provided from the MUX POD to the RTU unit 90 and sensors 86 and 88.
However, in case of an unexpected loss of control of the MUX POD, for example, explosion of the rig or vessel, even when all information related to the BOP stack is lost the sensors and/or valves are still functional and able to generate the information.
Therefore, it is desired to provide a capability to overcome the above noted problems.